Heat transfer problems in catalytic cracking fractionation towers
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This post was last edited by Desert Fish on 2016-4-5 at 10:12: ’( Hello, experts. I am currently working on the process design for a catalytic cracking unit, and I am facing many difficulties related to heat exchange in the distillation tower. The issues are as follows: the temperature of the heat circulating at the top of the distillation tower is low; I’m not sure how to make use of this heat. Using air cooling is somewhat wasteful, while using it in the reboilers of subsequent towers results in insufficient heat supply. The same problem occurs when using this heat in other applications, which forces the need to add additional steam to the reboilers of the desorption tower, stabilizer, and gasoline separation tower. Do you have any good suggestions for dealing with this situation? How does heat exchange work in conventional catalytic cracking distillation towers? Are there any useful software tools for optimization? Note: The feedstock is a light fractionated oil.
When the processing volume is low, it is not necessary to use air cooling; instead, increasing the circulation rate of the water cooler is sufficient. For high processing volumes, it is better to use air cooling
Heat the deionized water to provide low-temperature heat for the gas separation unit
The top circulation return of the newly designed catalytic unit exchanges heat with the reboiler at the bottom of the gas fractionation depropanizer; after this heat exchange, it exchanges heat with low-temperature hot water to supply heat for gas fractionation, the MTBE unit, and the heat tracing system. Thermal coupling is formed.
Do you mean that intermediate stream returning to the vaporizer to provide heat for the reboiler?
Sir, the temperature difference between our top reboiler and the depropanizer reboiler is less than ten degrees; it seems that heat exchange isn’t possible in this situation